The present invention relates to a structure for lubricating lips of oil seal assemblies that are typically used in combination with vehicular bearings on wheel shafts of electric cars for railway and the like.
FIG. 13 shows an oil seal assembly 1 with gutter spring which is a conventional type of oil seal assemblies for use in combination with vehicular bearings. The oil seal assembly 1 has a dust lip 11a and a main lip 11b that has a gutter spring 13 fitted on the outer circumference. It is a general manner that the oil seal assembly 1 is mounted by inserting it between a shaft S and a seal case 2 and then press-fitting a spring cover 3 into the space between the seal case 2 and an engaging portion 12a of a metal ring 12. The oil seal assembly 1 thus mounted has friction and wear occurring between the main lip 11b and the shaft S but the lubrication between these parts is not necessarily adequate since it relies on a small amount of the lubricant exuding out of a bearing J.
Unexamined Japanese Utility Model Publication No. Hei 6-32837 has proposed an oil seal assembly that provides a pair of metal rings that have portions engaging each other and that are disposed away from each other with a predetermined axial space in the axial direction and two rubber lips that are fixed to the inner peripheral edges of the associated metal rings. The axial space between the two metal rings is filled with plastic grease to supply a lubricant to the lips because the lubricant exudes out of the plastic grease.
This proposed manner, however, has the problem that it is unable to ensure satisfactory lubricating effects in a consistent manner for two primary reasons; i) an exuding point of the lubricant is away from the shaft; ii) grease filling and refilling operations are difficult to perform.